ON T H E L A W 0 F THE CONSTANGY 0 F T H E 

 QUANTI T Y 0 F HE AT. 



BY 



J. P. KUENEN. 



In writing tlie second volume of the new édition of Bosscha's Textbook 

 of Physics — Heat and Moleçular Porces — I was led into the considér- 

 ation of the fondamental conceptions and laws on which onr theory of 

 heat is based, and it appeared to me advisable to attempt to give a 

 somewhat more complète and especîally more exact définition and dis- 

 cussion of those conceptions and laws than is usually doue in textbooks. 

 Wliether I have been successf ul and., at the saine time, whether the attempt 

 to place before the readers of an elementary textbook a disquisition of 

 that nature was a wise one from an educational point of view, it is not 

 for me to décide. That the questions involved are of considérable impor- 

 tance, can hardly be denicd ; a fact to which testimony is borne by the 

 attention which in récent years lias been given by leading men of science 

 to similar problems and to the discussion of our physical conceptions 

 and théories generally. 



One of the earliest as well as most thorough and attractive investig- 

 ators of the problems referred to is E. Macu. His books on Dyna- 

 mics and on the theory of Heat are indispensable to anybody who recog- 

 nizes the necessity of a somewhat deeper insight into the nature of things 

 than is the share of the man in the street; his works may be said to 

 have opened up a field where philosophy and pure science eau and 

 should meet and common sensé rules with a strong hand. 



As regards the spécial problems in Heat, above referred to, they are 

 dealt with by Mac fi at considérable length. A not unimportant ques- 

 tion however obtruded itself upon me in trying to formulate my ac- 



